Gas-filled arresters, also known as gas arresters, are arresters in which the overvoltage is reduced in the gas arrester by automatic ignition of a gas discharge. They operate by the arc discharge principle, a principle determined by the physical properties of gases, wherein once an arrester sparkover voltage, also known as a sparkover voltage or triggering voltage, is reached, an arc forms in the gas-tight discharge chamber within nanoseconds. The high current-carrying capacity of the arc effectively short-circuits the overvoltage.
If an arrester is activated during surge current loading, charge carriers, in general electrons, of the cathode strike the anode, which on the one hand represents heavy loading for the anode material. It is also clear that the electrical properties of arresters, in particular insulation resistance after surge current loading, are impaired with an increasing number of instances of activation. In conventional gas arresters with two electrodes, it is in particular possible for conductive electrode material to be vapor-deposited on the ceramic internal wall. This leads to a reduction in the insulation resistance of the arrester. It may additionally lead to inadmissibly high leakage currents during operation at nominal AC voltages.
European Patent Application Nos. EP 2 648 292 A2 and EP 2 648 293 A2 describe a gas-filled discharge tube in which the ceramic material used has a special shape, whereby large-area vapor deposition on the ceramic material is prevented and insulation resistance after loading is increased.